IS 12633 I 198' (Reaffirmed 2000) Indian STandard FIRST FILLING AND EMPTYING OF PRESSURE TUNNELS - GUIDELINES '1llmtl qTifiti ~lil' ~ii l{1.:i\ ,,-n ~"1 ~~;1 ~) - ~l'tm fQ1't'( unc 627'842 I 62L·6 057 21 /"4 @ BIS 1989 BUREAU OF INDIAN STANDARDS ZAFAR MARG MANAK BHAVAN. 9 BAHADUR SHAH NEW DELHI 110002 Price Group :I AMENDMENT NO.1 AUGUST 1992 TO IS 12633: 1989 FIRST FILLING AND EMPTYING OF PRESSURE TUNNELS - GUlDELINES I Page I, clause 3.U. (I) ) -Insert tbe folloWingIllhe end: 'such IS lefl over ccncrete lumps. proJechons. protruding dowels. etc, Thesc ,bOuld be ground smooth.' I Page1, clause 3.1.1 (b) ) -Insert the following It the end: 'prdcJ1bl)' wllh rtSJD based hanlene rs,· I Page 1. clause 3.1.1 (c) ) -Inscrt Ihe Iollowmg Illbe end: 'IDd the boles Ior groulJng be SQIed perfectly Ind Ibe surface ground smooth.' (Page 3, clause 7.1.1 ) - Insert Ihe followmg Illhe end: 'TJus 'hall apply to penstock and draft tube gales atso, (RVD 14) ReP"'erapby VOl!,BIS, Now 0011.., Ind.. Water Conductor SYltelDl ~ctional Committee, BDC 58 FOREWORD Thil Indian Standard was adopted by the Bureau of Indian Standards on 24 February 1989, after the draft finalized by the Water Conductor Sylteml Sectional Committee had been approved by the Civil Engineering Division Council. The pressure tunnel is a part of water conductor IYltem and hence the filling and emptying is linked with overall planning of filling and emptying of the water conductor system. The schedule of first filling and emptyin~ of tunnel for a project shall be prepared and discussed among design and field engineers in detail before commencement of operation. IS 12633 I 1989 Indian Standard FIRST FILLING AND EMPTYING OF PRESSURE TUNNELS - GUIDELINES 1 SCOPE and precautions to be observed for first filling and emptying of the pressure tunnels of water conductor system of hydro-electric projects. 1.1 This standard covers the guidelines 2 GENERAL 2.1 Water conductor system of a hydro-electric project generally consists of the following components: a) b) c) d) e) f) g) h) j) Intake structure, Head race tunnels, Surge tank, Valve house, By-pass, Penstock,/presm re shafts, Draft tube, Downstream surge tank, and Tail race. 3 CHECK LIST 3.1 Before commencement of filling operation, it shall be ensured that all construction material, labour and d"partmental personnel are cleared from the entire water system. Before actually fiUing the system, the following checks ( 3.1.1 to 3.1.9 ) shall be exercised. 3.1.1 Intake Structure a) Trash-rack and air vent shall be cleaned and its cleaning device shall be checked. In projects where trash-rack cleaning device is not equipped, the racks shall be inspected manually. b) Gateslstop logs shall be checked for their seals, tracks, guides and smooth operation of gates. Filler valves shall also be checked, if provided. c) Hoisting arrangements shall be checked for proper operation. d) Automatic system for operation and alarm! shall be checked. e) A telephone/wireless set shall be provided at gate with trained crews posted for operation of gate. removed and the tunnel cleared of all extraneous material. b) It shall he repaired, wherever required. c) It shall be ensured that all cold joints are properly treated. d) It shall be ensured that contact grouting has been done in the prescribed reaches and shall be in accordance with the design requirements. e) It shall be ensured that consolidation grouting has been done in the prescribed reaches and shall be in accordance with the design requirements. f) It shall be ensured that all the points, such as, man-hole construction adits, etc, have been properly sealed/plugged in accordance with design requirements, g) It shall be ensured that all the instruments required for observations before filling, during filling and after filling have been installed at required locations and are in proper working order. h) Drainage holes and dewatering pipe, wherever provided, shall be checked and it shall be ensured that these are functioning properly and there is no particle flow. j) It shall be ensured that proper arrangements for gradual filling and dewatering are functioning properly. k) It shall be ensured that there is no obstruction in the air vent pipes, where provided, and around outlet and inlet pipes. m) It shall be ensured that the adit gates, where provided, are working and sealing have been bolted/locked properly. 3.1.3 Surg' Tank a) Gates/stop logs, wherever provided, in the surge tank shall be checked for their seals, tracks, guides, etc, by lowering/ rat-ing in respective slots or all the slots. It is also necessary to check filler valves to ensure balanced operation of gates. b) Hoisting arrangement for the above shall be checked for proper operation. c) Water level indicators, automatic system for operation and all the alarms shall be checked. d) Drainage glllleries, if provided, around the surge tank shall be cleaned. 3.1.2 Head Race Tunnel a) It shaH be thoroughly inspected. All the COJUtruction material/equipment shall be 18 12633 I 1989 e) Man holes, construction aditl, etc, shall be properly plugged in accordance with the design requirement. f) AIr vent shall be clear of any obstruction g) It shall he ensured that the lnstrumenu needed for observation before filling, during filling and after filling are installed at required places and are in working order NOTE - Tho above rhecka apply to upstream a. won as dowrutteam mrge tanka 3.1.4 Pens/ocks/Pressur, Shafts a) Entire length of penstocks/pressure shafts shall be thoroughly cleaned. The penstocks shall be painted and completed in all respects and inspected for before filling the wafer. b) All the machine inlet valves shan he checked for proper operation, c) All the bolts of man-holes shall be checked and tightened. d) All the bolts of the seals of expannon joints of penstocks should be tested and team kept ready with required kit to carry out tightening a. required in case of leakage. e) In case of rockers provided as supports for penstocks, these should be set and greased for free movement. f) Any instruments provided in pressure shafts or on anchor blocks shall be monitored. ~) It shall be ensured that grouting holes are properly plugged and repainted. h) It shall be ensured that the air vents are clear of any obstruction and air valves are working properly. j) It shall be ensured that filling and dewatering systems are working properly. pumping and followin~ systems in power house be checked f01 proper functioning: I) Operation of draft tube gates under water, 2) Cooling water system for power house, 3) Pressure filters In the power house, 4) Draft tube dell atermg system, 5) Emulsifier pumps in the power house, and 6) All drainage and dewatering system. e) In case of any malfunctioning, the tad race may be emptied by pumping and refilled after rer tifying the defects. f) The tall race and draft tube shall be filled up to minimum water level hefore the start of initia] fillmg. 3.1.7 Valve House The follo.... ing checks shall be carried out on valves before fillmg operation is started: a) All hydraulic and electrical systems should be checked b) The air inlet valve and vacuum breaking valves should be cleared for overflow of any water. c) The drain from the valve house should be cleared for overflow of any water. d) The communication between valve house and power house shall be tested. e) The control system from the control room to the valve house shall be checked and tested for proper operation. 5.1.8 Pow" House a) All pra-comrrussiomng test in the dry stage shall be completed in all respects and certified by the manufacturer and the erector. b) The staff required for the operation of power plant shall be In position and assume the specific duties. c) Adequate number of spare dewatering pumps shall be in posiiion at various floors of the power house. d) All temporary stofs provided during the construction shal be removed and tested against full tail race level. e) All drainage and dewatering pumps shall be conditioned and made in operational condition f) Turbine seals shan be tested and checked for perfect sealing. g) Inlet valve seals shall be tested and checked for perfect sealing h) Alternative source of power supply for working all auxiharies in the power house shall be ensured 24 hours. 3.1.5 Draft Tubes a) All the draft tubes shall be clean and ready for running. b) Draft tube gates and their hoisting arrangement shall be checked for their smooth operation. 3.1.6 Tall Race The fcllowrng checks 10 addiuon to those mentioned in 3.1.2 shall be carried out· a) The temporary cofterdam on downstream, if any, shall be removed. b) Pumps for dewatering the tail race should be ready at hand. c) The area around the tail race should be cleared of all obstructions for any immediate movement of equipment. d) After dry testing of draft tube gates, water should be filled in tall race by 2 IS 12633 I 1989 j) Electrical over head crane shall be in operating condition and tested. k] All vacuum valves and air release valve and drainage valves shall be tested. m) The security staff and security arrangement shall be completed to restrict the entry of unauthorized person in the power house. n) The staff fur operation and maintenance of the power house shall be in position and full compliment shall be detailed on shift duties bel ore rmtial fillmg starts. 6 CHECKS BEFORE START OF FILLING 6.1 Obtain final clearance ensuring that no man or material of any kind has been left In the tunnel and other works. The engineer in-charge shall himself inspect the tunnel and other works and ensure that no material or equipment has been left inside, before he orders closing of access doorsj man holes. 6.2 Check that access door.manholes are properly closed and locked. 6.3 Check that all the draft tube gates are In :J.l.9 By-Pa.s a) The garcs'stoplogs, where provided, shall be checked for their seals, track, guides, etc, by lowcung raismg in respective slots or all the slots as the case may be. b) It shall be ensured that the liners and embedded metal works are painted properly. c) It shall be ensilled that dlainage arrangernent around the by-pass has been provided in accordanee with design requirements. d) It shall be ensured that the air vents are clear of any obstruction. e) It shall be ensured that arrangement for gradual filling/dewatermg are functioning properly f) It shall be ensured that the alarm system indicating the sta: t of by-pass arrangement is working properly. 4 LOCATION OF OBSERVATION POINTS 4.1 Before filling the water conductor system, the observation points shall be judiciously located at convenient places along the aystem. Such points may be located near the tunnel plugs ( such as, those at intermediate adits in a long tunnel) and in the Vicinity of the surge shaft and along the penstocks slopes (say, in the upper expansion chamber). Observation points shall also be located at water systems, such as, existing springs, water level in wells, retaining walls, etc, in lower cover reaches and monitored after filling. If any leakage is observed at the observation point or an appreciable drop in surge tank water level is seen, the same shall be reported and attended to immediately. Since minor leakages through plug concrete may be anticipated, grouting equipment, such as, grout pump', pipes, nozzles, drilling machine, cement, sand, water, etc, shall be kept handy for urgent requirements. raised position. 6.4 Check that all the main inlet valves closed. are 6.5 Check that the guide vanes of all the machines are closed with 011 pressure applied (Apply generator brakes to prevent creeping, if necessary). 6.6 Check that the surge shaft gates/stoplogs are in open posiuon. 6.7 Check the reaervoir level. The filling should only start when the reservoir level is at or above the minimum permissible level. 7 FlLUNG OF THE SYSTEM 7.1 General Filling is normally done from the downstream end of the water conductor system, that is, the machine inlet valve. However, in case of long head race tunnel, where a surge shaft is provided, the system shall be filled initially up to the surge shaft, if provided with gates, otherwise up to the emergency valves downstream of valve. The portion of water conductor system between the emergency valves downstream of shaft and the main inlet valve provided just upstream of the machine may be filled up only afrer detection and rectification of leakage upstream of the butterfly valve. 7.1.1 The water conductor system shall be filled at very slow rate so that the internal pressure increases gradually and the surrounding conditions get sufficient time for stabilization. 7.1.2 In case of gated arrangement, the leakage on gates shall be checked and ascertained for the efficacy of the seals. 7.1.3 The water conductor system shall be filled at a slow rate so that there is no scope for the air to get entrapped, compressed and then released. 7.2 IJlidal FUUul 7.2.1 Depending upon the length of the system, number of probable seepage observation points and filling req uirements, the total time taken to complete the initial filling shall be estimated. This can be calculated and arrived at once the 5 COMMUNICATION FACILITIES 5.1 Communication facilities, such as, walkietalkie andjor telephone shall be provided at the intake as well as at all observation points so that important messages may be flashed across easily and quickly without any loss of time. 3 IS 12633 I 1989 volume of water required to fill the system is known. m) If the drop in water level is more at any step, the reasons for leak Igc shall be investigated and remedial measures should be taken. Next filling steps shall only be taken after ensuring that drop in water level in the prsceding 'Iep is within the pre-determined limit>. p) All gates, uoplogs, obser vation points, values and expansion poinn un penstocks shall be monitored for leakage dui ing and after filling. 7.2.2 Following steps shall he followed for initial filling: a) Gates of intake shall be lowered and pond level maintained at desired level with the help of spillway gates and/or other discharge outlets. h] Surge shaft gales/bulterfly valve and machine inlet valve gate shall be kept closed. c) If filling i, to he done by crack opening, intake gate shall he raiser! lip to the height calculated by e>timating the discharge requirements for filling up the system in the programmed schedule of time frame of filling. The velocity should be restricted to about 6 Ill/sec. The crack-opening would generally be of the order of 20 to 40 mm, Thus, in order to limit the velocity through the gate, water level in the reservoir should not be marc than 300 to 500 mm above the crest level of the intake sill. d) Surge shaft gates;butterfly valves, machine inlet valves, penstocks couplings., etc, shall be checked and tested. c) The tunnel shall be filled in appropriate pre-determined steps of water head so that excessive tension in the lining i. avoided, The steps may be worked out on the basis of known properties of the surrounding lock mass. 7.3 FUlial of Tail Race Syuem 7.3.1 The tail race shall be filled U t ' to the rn un mum tail ..... ater level gradually. In r ase of po wei houses having a clerp setting, the filling of the tail race may have to b~ accompliahed by pumping water into it from a Source located near the tail race. 8 EMPTYING THE SYSTEM 8.1 If quantity of leakage or any other situation warrants emptying the tunnel or entire water conductor system, following procedure and precaution, shall be adopted: a) Close all the intake gates, b) Emptying of the tunnel shall be done through the by· pass. However. if no bypass is provided, the water shall be dis. charged through the turbine. c) Before emptying the system through the turbine, it shall be ensured tbat the turbine is just sufficient to run the machine at no load and the generator is not being cnnnected. C) A waiting period of at least 48 h shall U,: allowed between first and second steps of filling and of at least 24 h between each subsequent ~teps of fillin~ to get the surrounding strata surchai ged with wafer g) Watel levels in the SUI ge tank shall be recerdecl concurrently during ihe fillin!; operation. h) At the end of each sfep of fiJling, the intake ~f.Ile~ shall be closed and water levels in the surge tank shall be observed every hour. The loss of water from tunnel through d rainagc galleries around SlIrge lank and leakage through machine inlet valve shall abo be noted.